Life Science in the News
August 2009 Produced by Ruth Watt, Modern Life Sciences Research Assistant
A New Rabies Treatment in the Works Reported in Nature, July 6, 2009. When a person is exposed to the rabies virus, the only treatment currently available is a set of five vaccination shots with inactivated rabies viruses given over a one month period. This treatment is “inaccessible to much of the developing world, where more than 99% of the 55,000 rabies deaths each year occur”. In addition, while weakened viruses produce a strong immune response, they also carry the risk of potentially causing the disease they are supposed to protect against. Scientists looking for a better way to attack the rabies virus modified genes in the virus that code for proteins found on its outside surface. Altering these surface proteins made the virus both less able to cause disease, and more able to promote a strong immune response. When the altered virus was injected into healthy, young mice, “pups as young as five days old did not show any signs of rabies. This means it’s a lot safer than other live attenuated vaccines that are out there”. When adult mice already infected with rabies were given the modified virus within three days of infection, the treatment eliminated the rabies virus from the mice. Scientists hope the treatment will be effective in humans beyond the time threshold of 20 hours after exposure in which current treatments must be administered. According to virologist Bernhard Dietzschold, “We showed we might be able to administer the vaccine later because we can clear the virus even after the onset of early symptoms.” When the research team tested the modified virus as a vaccine to protect against rabies infection, they found it conferred protection up to 3 weeks before exposure. The scientists hope to eventually develop a human vaccine “where one shot may protect for life”, and provide routine immunization for children in areas most at risk for rabies infection.
Tracking Penguins through Their Poop Reported in USA Today, June 2, 2009. Researchers are interested in finding and following emperor penguin colonies in order to monitor how well the penguin population is doing. Predictions of Antarctic ice shrinking by one-third its current size by the end of this century are considered a potential threat to these birds. Antarctica, however, has proven a difficult place in which to track emperor penguins. According to William Fraser, a researcher who has been studying penguins for 35 years, “The only time to see emperors are during breeding in winter when weather makes it nearly impossible to get to the colonies.” Scientists doing survey mapping noticed reddish-brown streaks on the ice in satellite images of Antarctica. Their discovery turned out to be “poop stains” from emperor penguin colonies. The colonies will stay in one place on the ice for months; this
apparently allows enough excrement—officially known as penguin guano—to collect that it can be visible from space. These stains were reported as visible “all over the continent”, and translated into the discovery of 38 emperor penguin colonies. The colonies included ten new penguin colonies, six colonies that had moved to new locations, and another six whose locations had been lost over time. Survey mapping scientist Peter Fretwell says, “It’s a very important result scientifically, even though it’s a lighthearted method.”
Kids’ Hair Gets Help from Stem Cells Reported in Bloomberg News, July 10, 2009. Alopecia areata is a disorder thought to be caused by the immune system attacking one’s hair follicles, leading to hair loss on the head or body. The hair loss can range from patchy to complete. In cases where the lost hair does not grow back, no approved treatments specifically for this condition exist. While alopecia areata can affect people at any age, dermatologist Marwa Fawzi from the University of Cairo says, “It’s an emotionally devastating disorder for children.” Fawzi conducted a small study in which children with alopecia areata were treated with their own hair follicle stem cells. These stem cells were first taken from the skin of the children’s scalps, then grown in a lab for one month. The cells were returned to the children’s scalps through a set of injections over their bald areas. Most of the children grew as much as half of their hair back. When the hair follicles of the children’s scalps were examined after the injections, Fawzi found “the injected stem cells had migrated in to the follicles”. The stem cells appeared to stimulate the follicles to come out of dormancy and generate hair. Fawzi plans to test the stem cell procedure in a larger study. If the procedure continues to be effective, it is possible it may be applied to male pattern baldness—a genetic condition leading to thinning hair all over the scalp in females, and a receding hairline and loss of hair from the crown of the head in males.
Borrowing Genes that Burn Fat Reported in Technology Review, June 8, 2009. Scientists have figured out a way to burn fat into carbon dioxide gas using a metabolic pathway found in plants and bacteria. The pathway, called the glyoxylate shunt, normally allows cells to convert fat into sugar, “and is used when sugar is not readily available or to convert the fat stored in plant seeds into usable energy”. BiomolecularEngineering Professor James Liao suggests humans may not have this pathway because “our bodies are designed to store fat rather than burn it”. A combination of only two enzymes (specialized proteins) makes the glyoxylate shunt reactions occur. When Liao and his research team first inserted the genes that code for these enzymes into human cells in the laboratory, fats were not only burned or metabolized faster, but also burned completely into carbon dioxide gas rather than just to sugar. The human cells were also encouraged to metabolize fats rather than sugar.
The researchers then inserted the genes for the glyoxylate shunt enzymes into the livers of mice. These mice “remained skinny” when put on a high-fat diet compared to normal mice in the control group. The mice also had lower fat and cholesterol levels in their livers compared to the control group. Rather than convert the extra fat in their diets into sugar—“which could have the dangerous side effect of promoting high blood sugar and diabetes”—the mice gave off extra carbon dioxide in their breath, so “the excess fat was literally released into thin air”. While humans don’t possess this particular fat-burning pathway, since the glyoxylate shunt is found in organisms such as chickens and rats, the genes for the shunt may still exist in a dormant form. For right now, this study may help in finding new ways to target obesity, if not through direct gene therapy, then perhaps through finding drugs which mimic glyoxylate shunt activity.
A New Way to Measure Age? Reported in BBC News, June 16, 2009. Scientists may have discovered a potential way to measure one’s age at a molecular level. According to the article, “concentrations of a protein called p16INK4a dramatically increases” as tissues age. The protein is normally present as part of the immune system, functioning to fight disease and repair damage to body tissues. The protein is also known for fighting the development of cancer. The scientists are in the process of “perfecting a simple blood test” that measures the level of the p16INK4a in one’s circulatory system. When used to analyze blood samples from 170 people who also reported on their overall health and lifestyles, the presence of the protein was shown to be affected by behaviors such as tobacco use and physical activity level—both known to affect how the body ages. Surprisingly, p16INK4a levels were not linked to obesity, suggesting “a lack of exercise may have a more profound impact on molecular aging than being overweight or obese”. Researcher Dr. Norman Sharpless from the University of North Carolina says, “This is a major step toward a practical tool to clinically determine a person’s actual molecular, as opposed to just their chronological age.” While Norman acknowledges the test may not apply to all types of human tissues, he suggests the test may be useful in determining how well tissues are fit for transplantation, or how well they will respond to chemotherapy or surgery.
Pollution and IQ Reported in Time, July 23, 2009. Polycyclic aromatic hydrocarbons, or PAHs, are given off during the incomplete burning of fossil fuels. Exposure to high levels of PAHs has been tied to lower birth weights and delayed motor development in children. Now a study has come out linking high PAH exposure during pregnancy to a decrease in IQ in children. As part of a study started in 1998 involving 249 children, the children’s mothers carried air-sampling equipment for 48 hours while in their third trimester of pregnancy. Those in the “high-PAH-exposure” group showed a four-point drop in their children’s IQ scores
by the time the children had reached 5 years of age. Frederica Perera, lead author of the study, explains, “A difference in four points could be educationally meaningful in terms of school success. The effect is comparable to the damage seen in children exposed to low levels of the toxic metal lead.” It is known that the developing fetal brain does not possess all of the proteins that function as detoxifying and repair enzymes in adults. This leaves the prenatal brain “particularly vulnerable to neurotoxic chemicals”, although exactly how PAHs cause damage is unknown. Epidemiologist Kimberly Gray from the National Institute of Environmental Health Studies says, “It’s surprising the effects [of prenatal exposure] are so persistent.” The study will follow the children through age 11 so the researchers can look for additional links between PAH exposure and learning disorders such as attentiondeficit disorder.